Luke Wilson (18), whose uncle John was shot dead at his home in Dublin last year, was fighting for his life as a young man was being questioned by gardai about the attack.

Officers think the attack could be linked to another shooting in the Ballyfermot area of west Dublin over a year ago that arose from a row involving dissident republican supporters and a local group.

But detectives say they are investigating a number of theories, including a possible link to an incident in Ballyfermot about a week ago.

Mr Wilson was targeted as he walked through Irish National War Memorial Park near Inchicore at about 3pm yesterday. The gunman ran towards him as he walked close to a footbridge near the Liffey Gaels GAA club in the park.

He was shot twice in the head and once in the neck with what gardai believe was a low-calibre weapon.

As the gunman fled, the victim managed to use his mobile phone to make a 999 call for help.

Last night, he was in a critical condition at St James's Hospital where he was undergoing surgery and a scan as surgeons battled to save his life.

Gardai carried out a number of searches in Ballyfermot throughout the afternoon and these led to the arrest of a 19-year-old suspect, who was being held for questioning last night at Kilmainham garda station.

The teenager was shot close to a pedestrian bridge, which links Memorial Park with playing fields behind the Liffey Gaels GAA pitch.

Residents expressed shock at the violent incident, which happened close to where children play hurling and football.

It was the second shooting in the area in less than three years. Anthony Cannon was shot dead on the road close to the GAA club in 2009 in an incident believed to be part of the Crumlin-Drimnagh feud.

Liffey Gaels GAA club barman Damien Kellegher said he was at work yesterday but had not seen the gunman.

"The first thing I knew about it was when I saw a few gardai running across the fields," he said.

Mr Wilson has lived with his grandmother Kathleen Wilson, at nearby Cremona Road in Ballyfermot, since his own mother died of a drug overdose, and was raised by her and his uncle, John, who was gunned down at his home in September.

Two other uncles, Eric and Keith, are behind bars on murder convictions, the former in Spain and the latter here.

John Wilson had a long history of involvement in organised crime and had been convicted of weapons offences.

He was arrested by gardai in connection with a shooting in the Player's Lounge pub in Fairview in 2010, which left three innocent men seriously injured.

Eric Wilson is in a Spanish prison, following his conviction for the killing of another man.

Luke Wilson has previously appeared at the Children's Court in connection with a number of offences, most recently last week when he was fined €500 for driving without insurance.

His grandmother, Kathleen Wilson, was also charged in relation to the assault of the mother of the man accused of killing John. Ms Wilson, who is in her late 40s, allegedly broke into the family home of Keith O'Neill in Ballyfermot and confronted his mother Margaret O'Neill (80). It is claimed the alleged assault took place just weeks after Ms Wilson appealed for an end to the violence.

Shooting

Last night, there was no one home at Ms Wilson's semi-detached house in Ballyfermot and neighbours were reluctant to talk about the shooting.

Liffey Gaels GAA chairman George O'Gorman said parents had called the club after hearing reports the shooting had taken place on the premises.

There were no games or training taking place at the time, he said, but parents had become concerned.

"It is shocking. We had parents getting on to us to find out what had happened. Obviously when you're investing so much in juvenile games, the last thing you want is parents to think there was a shooting in the clubhouse."